Sociality is the dimension of behavior that brings organisms into association with others, especially other members of one's species and affords all the vital interactions that represent phenomena such group affiliation, mate choice, parental behaviors, information exchange, and altruism. Sociality exists on the level of the individual and on the level of the group, and each has a separable, but interrelated development. The proposed research is designed to define and identify the onset of sociality in Mus musculus, the major model mammal serving the NIH Roadmap. We propose a program of research that will employ observational, experiential, physiological, genomic and neuroendrocrine approaches to recognizing when social responses are first expressed by infant mouse pups, how their social behavior becomes directed at other mice, and the rules that govern individual and group behavior. The Specific Aims of the proposed research include: establishing for the C57 strain of laboratory mouse, a set of group and individual phenomena that represent their early social behaviors; creating parametric, foundation data on metabolic effort by individuals and groups so that physiological (especially thermal) effects of contact behavior can be separated from non-thermal, social affiliations. Throughout the research, we will also invoke selected genetically-engineered (knock out) mice to both test specific hypotheses concerning the roles of cutaneous temperature sensation and the central oxytocin in the formation and expression of filial behavior. Sociality in individual development will be analyzed, especially the development of olfactory preferences that make specific individual's filial responses. Novel olfactory isotopes will be used to discover the developmental determinants that derive from specific experiences in the nest with mother and littermates. These constitute probes into how natural experiences serve as learning mechanisms in behavioral development. Finally, we will provide both global and specific measures of maternal behavior in the C57 mother mouse, for these data and their methods are needed for complete analyses of genetic and other experimental contributions to development, since many of these manipulations can operate by altering in maternal behavior. Maternal responses to genomically-altered litters and individuals will be studied to test these ideas. PUBLIC HEALTH RELEVANCE: The importance of the proposed research will be seen first in its contribution to linking objective and quantitative metrics of social behavior to modern knowledge of gene expression and endocrine processes in the brain. This linkage in a mouse model will provide a needed research tool for testing treatments for the many forms of mental illness, such as the autism spectrum disorders and schizophrenia, that involve fundamental disruptions in social processes and social responses.